You can map a Hubspot dropdown to a Salesforce text field (in that direction). Ignore the warning - it’ll work as long as the options follow your text field validations.

You may have some unwanted results when free text that’s not a dropdown option originates from Salesforce and syncs back into Hubspot. It’ll create new options for the Hubspot property for each unique text value. Depending on who/how the field is being used, it could get out of control. (speaking from experience)